Gum massaging oral brush

ABSTRACT

An oral brush is provided that includes an elongated body, a head portion extending from the body, and a plurality of bristles, formed of particular thermoplastic elastomers, extending from the body. In various embodiments, the thermoplastic elastomer has a Shore A hardness of at least 30; the thermoplastic elastomer is selected from the group consisting of polyetheramides, polyesters, styrene-ethylene-butylene-styrene block copolymers, polyurethanes, polyolefin elastomers, and mixtures thereof; and the thermoplastic elastomer has a flexural modulus of at least 5 MPa.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation (and claims the benefit of priorityunder 35 U.S.C. § 120) of pending U.S. application Ser. No. 11/248,087,filed Oct. 12, 2005, which is a continuation of U.S. application Ser.No. 10/991,911, filed Nov. 18, 2004; which is a continuation of pendingU.S. application Ser. No. 10/692,916, filed Oct. 24, 2003; which is acontinuation of pending U.S. application Ser. No. 10/036,022, filed Dec.26, 2001; which is a divisional of U.S. application Ser. No. 09/660,151,filed Sep. 13, 2000, now abandoned; which is a continuation of U.S.application Ser. No. 09/351,588, filed Jul. 12, 1999, now U.S. Pat. No.6,151,745; which is a continuation of U.S. application Ser. No.08/730,286, filed Nov. 30, 1996, now U.S. Pat. No. 5,987,688; which is acontinuation-in-part of Ser. No. 08/554,931, filed Nov. 9, 1995, nowabandoned.

BACKGROUND OF THE INVENTION

The invention relates to oral brushes and bristles for use in oralbrushes.

Most humans suffer from tooth decay and/or gingivitis caused by bacteriain the mouth. As a result, decreasing the amount of plaque in the mouthhas long been the target of persons working in the health care field. Acommon way of minimizing the plaque in the mouth is to brush the teethregularly.

However, the benefits of frequent brushing can be accompanied in someinstances by deleterious side effects such as irritation, abrasion andeven recession of the gums. These side effects may, in part, result fromexcessive stiffness and/or sharpness of the toothbrush bristles.

Another common way of improving oral health is by massaging the gums tostimulate the gingival tissue. Conventional toothbrushes tend to havelimited effectiveness for gum-massaging, and thus often a separategum-massaging procedure, using a gum-massaging tool, is required toensure good oral health.

Endeavors have been made to reduce gum irritation and/or provide agum-massaging effect by replacing some or all of the toothbrush bristleswith rubber or synthetic rubber pins. See, e.g., U.S. Pat. No.4,288,883.

SUMMARY

The invention features improved gum-massaging oral brushes which providegood comfort and gum stimulation while also providing good cleaning ofthe teeth. The invention also features bristles for use in gum-massagingoral brushes.

In one aspect, the invention features an oral brush including anelongated body, a head portion extending from the body, and a brushportion including a plurality of bristles formed of a thermoplasticelastomer extending from the body. The thermoplastic elastomerpreferably has a Shore A hardness of at least 30; is selected from thegroup consisting of polyetheramides, polyesters,styrene-ethylene-butylene-styrene block copolymers,styrene-butadiene-styrene block copolymers, styrene-isoprene-styreneblock copolymers, polyurethanes, polyolefin elastomers, and mixturesthereof; and has a flexural modulus of at least 5 MPa.

Preferred oral brushes further include a plurality of bristles formed ofa non-elastomeric material. In preferred embodiments, this material isselected from nylon, polyamides, polyesters andpolybutyleneterephthalate (PBT). The non-elastomeric bristles mayinclude additives to improve their cleaning ability, e.g., abrasives andpolishing agents such as clays, silicas, aluminas, calcium carbonate,calcium or magnesium phosphate compounds, apatites, and mixturesthereof.

Preferred oral brushes also include a spacer attached to the base of thehead portion. The spacer is formed of a thermoplastic elastomer and isintegrally joined to the bristles. Preferably the non-elastomericbristles extend from the head portion through the spacer.

In another aspect, the invention features an oral brush including aplurality of bristles formed of a thermoplastic elastomer, and aplurality of bristles formed of a polyphthalamide.

In another aspect, the invention features massaging the gums with one ofthe bristles described previously.

An oral brush, as used herein, is any brush that includes a body havinga brush portion designed for insertion into the mouth. The brush portionincludes a plurality of bristles extending therefrom and beingdimensioned to be used to brush tooth surfaces.

In another aspect, the invention features an oral brush includingmulticomponent bristles, preferably comprising a thermoplastic elastomersheath surrounding a core material comprising a non-elastomeric materialor a thermoplastic elastomer having a higher hardness than thethermoplastic elastomer sheath. The invention also features methods ofmaking multi-component bristles, e.g., by coextruding a plurality ofpolymers. By “multicomponent”, we mean that the bristles have two ormore components; by “coextruded”, we mean that at least two of thecomponents are present in the form of substantially separate phaseshaving a distinct interface between them, rather than being intermixed.The bristles are preferably formed by processes which are referred to inthe art as “coextrusion”, but the term “multicomponent coextruded”, asused herein, encompasses bristles having the structure described abovewhich are manufactured by other processes.

The term “thermoplastic elastomer”, as used herein, refers tonon-vulcanized, rubbery polymeric materials which may be processed byconventional plastics processing methods which are well known in theart, such as extrusion or injection molding.

In another aspect, the invention features an oral brush including aplurality of bristles formed of a mixture including (a) anon-elastomeric polymer, such as a relatively hard base resin, e.g.,Nylon, polypropylene, or polybutylene terephthalate (PBT) and (b) athermoplastic elastomer such as a polyamide thermoplastic elastomer, apolyester thermoplastic elastomer or other olefinic thermoplasticelastomers. In some embodiments this mixture also contains additivessuch compatibilizers, abrasives and plasticizers.

In yet another aspect of the invention, the invention features an oralbrush including a plurality of bristles formed of a mixture including(a) a non-elastomeric polymer and (b) a soft (e.g., having a hardness ofless than 90 Shore A) vulcanized rubber-type polymer, such as naturalrubber, crosslinked polybutadiene, crosslinked polyacrylates and thelike. In some embodiments this mixture also contains additives such ascompatibilizers, abrasives and plasticizers.

Other features and advantages of the invention will be apparent from thedescription of the preferred embodiment thereof, and from the claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a oral brush.

FIG. 2 is a schematic top plan view of the head of an oral brushaccording to one embodiment of the invention.

FIG. 3 is a schematic top plan view of the head of an oral brushaccording to another embodiment of the invention.

FIG. 4 is a cross-sectional top view of a co-extruded bristle accordingto one embodiment of the invention.

FIG. 5 is a schematic diagram showing a process according to oneembodiment of the invention for forming a coextruded filament.

FIGS. 6 and 7 are perspective views of oral brushes having bristlesmolded

DETAILED DESCRIPTION

Referring to FIG. 1, a toothbrush 10 includes a plastic body having ahandle 12 and a head 14 attached to a bristle portion 16.

The body of the toothbrush is formed by conventional methods well-knownin the art. The handle is shaped to be grasped by a hand, butalternatively can be shaped to fit into an electric toothbrush. Theconfiguration of the head can vary and may be rectangular, oval,diamond-shaped, or any other shape, with bristles which are trimmedflat, serrated, v-shaped, convex curved, or any other desiredtopography, as is well known in the art. The shape and size of handle 12and head 14 can vary and the axes of the handle and head may be on thesame or a different plane. It may be desired to provide a larger headthan is conventional, in order to provide extra room for thethermoplastic elastomer bristles, while still retaining the standardnumber of non-elastomeric bristles.

Brush portion 16 includes a number of non-elastomeric bristles 18 and anumber of elastomeric bristles 20. Preferably, as shown in FIG. 2, thenon-elastomeric bristles extend from the central portion of the head 14and the elastomeric bristles are disposed around the outer perimeter ofthe head 14, surrounding the non-elastomeric bristles. Another possiblearrangement is shown in FIG. 3.

The non-elastomeric bristles are formed of tufts of individual filamentsattached to the head in manners known to the art. The elastomericbristles are formed of tufts of one or more filaments of thermoplasticelastomer. If a single filament is used per tuft, the filamentpreferably has a diameter that is half that of a standard pre-cored tufthole, e.g., 33 mil for a 66-mil pre-cored hole, so that the filament canbe folded and staple tufted into the hole.

Alternatively, some or all of the bristles are formed of a mixture ofelastomeric and non-elastomeric polymers. The elastomeric material isselected from the group consisting of thermoplastic elastomers andvulcanized rubber-type polymers. In both cases, the ratio of theelastomer to the non-elastomeric material is preferably from10:90-90:10. Preferred bristle diameters range from 3-100 mil (taperedor untapered), depending on the mixture used and elastomer andnon-elastomeric material chosen as would be understood by one skilled inthe art.

Suitable filaments formed of a blend of elastomeric and non-elastomericinclude, but are not limited to the following: Processing DrawdownComposition Temp Ratio Diameter Bend Recovery 30% Pebax 2533 250° C. 4:18 mil 95% 70% Zytel 151L 30% Pebax 2533 250° C. 4:1 7 mil 95% 70% Zytel151L

Such a mixture can be compounded using standard processing proceduressuch as a single screw or twin screw extruder or dry blending.

Suitable thermoplastic elastomers are those which have sufficientstiffness and hardness for effective gum massage and to resist tearingand/or excessive wear during use, while being sufficiently soft toprovide comfort and avoid gum irritation during gum massage. Suitablethermoplastic elastomers include polyetheramides, e.g., PEBAX polymers(ELF Atochem); polyesters, e.g., HYTREL polymers (DuPont);styrene-ethylene-butylene-styrene block copolymers,styrene-ethylene-propylene-styrene block copolymers,styrene-butadiene-styrene block copolymers, and styrene-isoprene-styreneblock copolymers, e.g., KRATON rubbers (Shell); polyurethanes, e.g.,PELLETHANE polyurethanes (DOW); polyolefin elastomers, e.g., SANTOPRENEelastomers (Advanced Elastomer Systems); and mixtures thereof.Poly(ether-amide) block copolymers having the general formula

where PA=polyamide segment and PE=polyether segment, commerciallyavailable under the tradename PEBAX polymers, are particularlypreferred. Of these, a copolymer of nylon 12 and poly(tetramethyleneglycol) commercially available under the tradename PEBAX MX-1205 polymeris particularly preferred. Another preferred thermoplastic elastomercomprises a blend of a polyamide sold under the tradename PEBAX 2533 anda block copolymer sold under the tradename KRATON G-6713, preferablycontaining about 90% of the polyamide and 10% of the block copolymer.This blend provides good softness without tackiness or weakness.

If a relatively soft thermoplastic elastomer is used, a relatively largediameter filament may be needed to provide sufficient durability andstiffness. Such large diameter filaments preferably have a diameter lessthan about 200 mil, more preferably 30 to 100 mil. If a harder, stifferthermoplastic elastomer is used, a smaller diameter filament can beused. Generally, suitable thermoplastic elastomers will have a Shore Ahardness of at least 30, preferably from about 35 to 55 and a flexuralmodulus of from about 5 to 100 MPa.

Suitable vulcanized rubber type polymers include, but are not limitedto, natural rubber, crosslinked polybutadiene, cross-linkedpolyacrylates, and blends thereof.

Non-elastomeric bristles 18 may be formed of any material suitable foruse in toothbrush bristles. Such materials can also be used as thenon-elastomeric component of elastomeric non-elastomeric blend bristles.Preferred materials include nylon 612 and other polyamides. A preferredgrade of nylon is available from Whiting Co., Burlington, Vt. under thetradename WYTEX. Preferred polyamides include polythalamides sold byAmoco Performance Products, Inc., under the tradename AMODEL resins.Such polyphthalamides are described in U.S. Pat. Nos. 4,603,166,4,476,280, and 4,617,342, the disclosures of which are incorporatedherein by reference. A particularly preferred polyphthalamide is acrystalline polyphthalamide formed by polymerization of terphthalicacid, isophthalic acid and adipic acid with hexamethylene diamine. Othersuitable filaments include acetal resins, polyesters, fluoropolymers,polyacrylates, polysulfones and combinations thereof. Preferrednon-elastomeric filaments have a diameter of from about 3 to 10 mil.

In an alternate embodiment, the elastomeric bristles include a sheath 30of thermoplastic elastomer coextruded around a core 32 of a differentmaterial, as shown in cross-section in FIG. 4. The sheath to core volumeratio may be from 95:5 to 5:95.

Preferably, the core material is a stiff polymer, allowing the outersheath to be softer and/or allowing the bristles to have smallerdiameters than would otherwise be possible (with a thermoplasticelastomer alone) due to the constraints of bristle durability andstrength. If desired the coextruded filaments can have standard bristlediameters, e.g., 5-8 mil. Preferred filament diameters range from 5 to65 mil, depending on the application in which the bristle is to be used.Suitable core materials include but are not limited to polyamides, e.g.,nylons, and polyesters, e.g., PBT.

Preferred sheath materials include the thermoplastic elastomersdiscussed above. Softer grades of these elastomers can be used when astiff core is provided, e.g., the sheath material may have a hardness aslow as 3 Shore A.

A suitable method for forming the coextruded filaments is shown in FIG.5. As shown, the two components are extruded through first and secondextruders to form a filament, after which the filament is passed througha water bath, and through a series of godets. The filament is placedunder light tension as it travels between two drawing godets which arerotating at different speeds. The tension applied to the filament isexpressed as the “drawdown ratio”, which is the speed differentialbetween the two drawing godets. Preferred drawdown ratios are from about1.0 to 7.0. The filament then passes through a relaxing godet and iscollected on a take-up winder. Suitable coextruded filaments include,but are not limited to, the following: Composition (Sheath/Core) VolumeRatio Drawdown Rat. Diameter PEBAX MX1205/ 10:90 4:1  8 mil Nylon 612PEBAX MX1205/ 50:50 1:1 or 2:1 55 mil Nylon 612 Blend of 90% 10:90 or50:50 4:1  8 mil PEBAX 2533 and 1:1 or 2:1 55 mil 10% DYNAFLEXG6712/Nylon 612 HYTREL 3078/ 10:90 or 50:50 4:1  8 mil Nylon 612 1:1 or2:1 55 mil

In an alternate embodiment, head portion 14 includes bristles 20integrally joined to spacer 40, which is attached to the base of headportion 14, as shown in FIG. 6. Spacer 40 provides good adhesion ofbristles 20 to head portion 14 and provides support to bristles 18. Theadditional support provided by spacer 40 stiffens bristles 18 bydecreasing the effective length of the bristles, which allows theincorporation of bristles having smaller diameters that more easilypenetrate the interstitial regions of the mouth into the toothbrush.Bristles 18 extend from head portion 14 through spacer 40. Spacer 40 isformed of the elastomeric materials listed above and can be formed ofthe same elastomeric material as used to form the elastomeric bristles20. Spacer 40 and elastomeric bristles 20 at the perimeter of headportion 14 can be molded as one unit. If the bristles 20 and spacer 40are molded as one unit, their diameter is preferably from about 4 mil toabout 200 mil. Elastomeric bristles 20 can extend at angles from spacer40 and can optionally extend from the head portion to a radiusedterminal end 71.

Alternatively, spacer 40 can be recessed into head 14 such that thebristle receiving surface 46 of spacer 40 is substantially contiguouswith surface 44 of head portion 14, as shown in FIG. 7.

Other embodiments are within the claims. For example, if desired, all ofthe bristles may be formed of thermoplastic elastomer material. Thebristles may be formed of a blend of thermoplastic elastomers. Moreover,the oral brush may include elastomeric bristles having differentrelative compositions, e.g., some of the bristles are formed of a firstthermoplastic elastomer or blend of elastomers and other bristles areformed of a different thermoplastic elastomer or blend. Further, theelastomeric bristles may include other polymers, e.g., plasticizers suchas oils, waxes or resins to increase softness, or additives, e.g.,fillers, antioxidants, UV stabilizers, and abrasives or polishingagents. Suitable polishing agents include particles of plastic,particles of walnut shells, particles of hardwood, particles of corncob, particles of rubber, calcium carbonate, aragonite clay,orthorhombic clays, calcite clay, rhombohedral clays, kaolin clay,bentonite clay, dicalcium phosphate, dicalcium phosphate anhydrous,dicalcium phosphate dihydrate, tricalcium phosphate, calciumpyrophosphate, insoluble sodium metaphosphate, precipitated calciumcarbonate, magnesium orthophosphate, trimagnesium phosphate,hydroxyapatites, synthetic apatites, alumina, hydrated alumina, hydratedsilica xerogel, metal aluminosilicate complexes, sodium aluminumsilicates, zirconium silicate, silicon dioxide, and combinations thereof

1. A toothbrush, comprising: a handle; a head attached to the handle,the head comprising a plurality of non-elastomeric bristles and aplurality of upstanding elastomeric elements, wherein the plurality ofupstanding elastomeric elements are disposed along a perimeter of thehead; and an elastomeric portion attached to the head and formed in arecess therein, wherein the plurality of upstanding elastomeric elementsand the elastomeric portion are molded as a unit so that the elastomericupstanding elements are integrally joined to the elastomeric portion. 2.The toothbrush of claim 1, wherein the elastomeric portion has a topsurface that is substantially contiguous with a surface of the head. 3.The toothbrush of claim 1, wherein the upstanding elastomeric elementsare formed from a thermoplastic elastomer having a Shore A hardness ofat least about
 30. 4. The toothbrush of claim 3, wherein thethermoplastic elastomer is selected from the group consisting of naturalrubber, polyacrylates, polybutadienes, polyetheramides, polyesters,styrene-ethylene-butylene-styrene block copolymers,styrene-ethylene-propylene-styrene block copolymers, styrene-isopreneblock copolymers, polyurethanes, polyolefin elastomers, and mixturesthereof.
 5. The toothbrush of claim 4, wherein the thermoplasticelastomer has a Shore A hardness between about 35 and about
 55. 6. Thetoothbrush of claim 4, wherein the thermoplastic elastomer has aflexural stiffness of at least about 5 MPa.
 7. The toothbrush of claim4, wherein the thermoplastic elastomer has a flexural modulus betweenabout 5 and about 100 MPa.
 8. The toothbrush of claim 1, wherein theplurality of non-elastomeric bristles are alternatingly arranged withthe plurality of upstanding elastomeric elements.
 9. The toothbrush ofclaim 1, wherein the upstanding elastomeric elements are configured tomassage gums of an oral cavity.
 10. The toothbrush of claim 1, whereinthe plurality of non-elastomeric bristles are inserted into a pluralityof holes.
 11. The toothbrush of claim 10, wherein the plurality ofnon-elastomeric bristles attached to the head by stapling.
 12. Thetoothbrush of claim 1, wherein the head has a first side surface and asecond side surface and between about 4 and about 7 upstandingelastomeric elements are arranged adjacent the first and second sidesurfaces.
 13. The toothbrush of claim 1, wherein the toothbrush is anelectric toothbrush.
 14. The toothbrush of claim 1, wherein theelastomeric elements comprise an abrasive.
 15. A method for forming atoothbrush having a handle and a head attached to the handle,comprising: molding an elastomeric portion in a recess of the head andmolding a plurality of upstanding elastomeric elements, wherein theelastomeric portion and the plurality of upstanding elastomeric elementsare molded as a unit so that the upstanding elastomeric elements areintegrally joined to the elastomeric portion and wherein the elastomericportion has a top surface that is substantially contiguous with asurface of the head; and attaching a plurality of non-elastomericbristles to the head, wherein the plurality of non-elastomeric bristlesare inserted into a plurality of holes.